Web-fed printing devices are commonplace and can be found, for example, in industrial or retail printing environments. Web-fed refers to the webs, or rolls, of media, being fed into the printing devices and are distinguishable from sheet-fed printers. Sheet-fed refers to individual sheets of media being fed into the printing device. The media can include paper, polymeric materials, or other media adapted for printing. Sheet-fed printing devices offer the advantages of being configurable for different format sizes and waste sheets can be reused for testing, which can lead to flexibility and lower cost print preparation. Web-fed printing devices, however, provide much faster printing than sheet-fed devices. The speed of web-fed printing devices makes them ideal for large runs such as newspapers, magazines, and books.
Web-fed printing devices can be used for offset, or analog, printing or for digital printing. Offset printing is a commonly used printing technique in which the inked image is transferred, or offset, from a plate to a rubber blanket, then to the printing surface. When used in combination with the lithographic process, which is based on the repulsion of oil and water, the offset technique employs a flat, or planographic, image carrier on which the image to be printed obtains ink from ink rollers while the non-printing area attracts a water-based film, or fountain solution, to keep the non-printing areas free from ink. Digital printing refers to methods of printing from a digital based image directly to the media. Digital printing can refer to professional printing where print jobs from desktop publishing and other digital sources are printed using large format or high volume laser or inkjet printers. In some circumstances, digital printing has a higher cost per page than more traditional offset printing, but the price is usually offset by the cost saving in avoiding steps to make printing plates. It also can more easily provide for on demand printing, short turn around, and even a modification of the image (variable data) with each impression.